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Discussion Starter · #1 ·
Over the last few weeks I have noticed some strange engine noise when I drive it cold and if I accelerate to quickly(over 2500 RPMs), the engine will produce a rattling/grinding sound. It doesn't sound good and only does it when it is cold. Any ideas on this? I have looked the engine over completely and can't find anything that is loose and if it was something loose I would imagine it would rattle regardless if the engine was hot or cold. The timing seems to coincide with my last oil change I did where I put in Mobile1 15w-50 Synthetic and the Mobile1 filter. The only thought that came to my mind was that maybe the oil isn't being properly distributed when its cold and if I accelerate too quickly its the rods and valves complaining because they aren't properly lubricated?

Any thoughts/ideas would be appreciated. I obviously want to remedy this before it turns into something catastrophic.

Thanks,

Hank :eek:
 

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Cold engine piston slap maybe??
 

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Piston slap might sound like a rattle but not a grinding.

I say first, rule out the engine accessories by removing the belts and start the engine. It is common for an bad alternator bearing to sound this way.
 

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Sounds like an oil filter inspection is in order......
 

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Discussion Starter · #6 ·
The timing coincides with the change over to synthetic. And what are you thinking on the oil filter Chuck?

Thanks,

Hank
 

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I'd cut it..

The timing coincides with the change over to synthetic. And what are you thinking on the oil filter Chuck?

Thanks,

Hank
open and see if the engine is shedding some of it's "skin"...:eek:
BE SURE to use a cutter that doesn't make dust..IE, a pair of snips.
if you still have the old filter that was on the engine B4 you made the oil change, I'd cut it too, and make a comparison..Problem may have started B4 U changed to Mobil1, and just hadn't gotten to the making noise part....
 

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The timing coincides with the change over to synthetic. And what are you thinking on the oil filter Chuck?
Thanks,
Hank
I think the timing is pure coincidence. Synthetic oil is still just oil.

Think simple before you think complicated. Make sure the engine is what's making the noise before you start looking there.

Start the engine cold without the belts.
Noises can fool you and it's really easy to remove the belts and make sure.
 

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Engine Noises

I ran into the same concern when I changed to Mobil One synthetic oil. I found the noise I heard came from main bearings and was always there but changing to Mobil One(thinner?) oil revealed the noise. Experimenting, I reversed course and installed Castrol 20W50. Whadda ya know. No Noise. Engine tear down revealed badly worn bearings overall, with two scored severely. One bottom end job later, Mobil One in the crankcase = no more noise.
Hope you have better luck,
Regards,
JW
 

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Discussion Starter · #10 ·
Update:

The noise doesn't occure when in neutral and reving the engine, it only surfaces when I have the vehicle in gear...including reverse. I am finding that now it has nothing to do with the engine being cold or not, it happens moreso when it is cold(especially if I backup before it warms up, when backing up it sounds like baseball cards in bicycle spokes), but even after it is warm and I punch the gas it makes the disturbing rattle. It has gotten worse over time but the odd thing is it seems like if I let it rattle enough it goes away.

Not sure what to do from here. One thing I also did change before this sound surfaced was the manual speedo cable(still didn't resolve my non-functioning speedo), think that could have anything to do with it?

Thanks for any input.

Hank
 

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One thing I also did change before this sound surfaced was the manual speedo cable(still didn't resolve my non-functioning speedo), think that could have anything to do with it?

Hank
HUm, tak speedo cable out and use liquid grafite<sp> on cable and reinstall, and see if noise disappears
keep us posted
 

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Update:
The noise doesn't occure when in neutral and reving the engine, it only surfaces when I have the vehicle in gear...including reverse. I am finding that now it has nothing to do with the engine being cold or not, it happens moreso when it is cold(especially if I backup before it warms up, when backing up it sounds like baseball cards in bicycle spokes), but even after it is warm and I punch the gas it makes the disturbing rattle. It has gotten worse over time but the odd thing is it seems like if I let it rattle enough it goes away.
Not sure what to do from here. One thing I also did change before this sound surfaced was the manual speedo cable(still didn't resolve my non-functioning speedo), think that could have anything to do with it? Thanks for any input.Hank
That pretty much rules out engine accessories and piston slap.

Make sure your clutch inspection cover isn't warped and hitting the flywheel. I had that happen once.
 

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Is it automatic or manual? Sorry, I didnt seem to notice in these posts? If auto, check speedo gear and funny enough check linkage for firm park release! if linkage was out (especially in reverse)or spring broken on park dog in pan it might be hitting high-reverse clutch drum? If manual, check speedo cable, or inspection cover? Just a few thoughts, after the speedo cable and the converter fly-wheel dust cover next easiest thing is to drop the pan and check park dog?
 

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Engine Noise

Inspect for loose or worn out motor mounts, which may allow fan (w or w/o clutch) to nick fan shroud. This would happen more often when in gear. As Roger1 posted earlier, think simple things first.
Regards,
JW
 

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For 10 bucks of cost, drain oil and put something else in and see if the noise is related to the oil. I don't know why it would make a difference, but reading your post you are suspicious of it for sure. Leave same oil filter. Is it possible the filter pressure valve isn't working and bypassing the filter when cold and causing problems. This all seemed to happen when you changed the oil. Kurt
:anim_25:
 

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Discussion Starter · #16 ·
Update

The strange noise has progressively gotten worse to the point that it is now happening when the car is in park and I rev the engine over 2k RPM. It happens now ALL the time driving when accelerating in the 2-3k RPM range and then once in 4th it seems to stop. I took it to one mechanic and he couldn't figure it out, said in his opinion it wasn't the engine nor the transmission but needed to start tearing stuff a part to confirm...he believed it was possibly something inside the exhaust.

This past weekend I put it up on stands and checked for anything loose, fixed one exhaust mount that was allowing the metal to hit the frame, had to adjust the parking brake cable as it was hitting the drive train, checked for loose bolts on the stall converter(were none), tightened bolts on oil pans for engine and trani, checked and tightened the motor mounts...and still have the sound.

I have made a recording(the link below will take you there....you can hear it best at the end where I was between two walls) of the sound, hopefully this will ring a bell with someone out there. The other thing I have read mentioned as a possibility is a bad catalytic converter but not sure my exhaust even has those....it has muffler boxes towards the back and I tapped them lightly with a hammer and they sounded hollow.

Anyway, any ideas, thoughts, suggestions would be appreciated.

Strange Rattle
 

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Hank, that does sound like something in the exhaust system. Do you have a heat riser valve on the passenger side exhaust manifold where the exhaust pipe connects? The spring can break and they can flop around.
Or do you have headers? Maybe an exhaust leak. They can make strange noises.
 

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Hmmm I had a 57 once that the starter bendix went bad and was engaging the flywheel off and on and as I recalled it did sound like cards in a bike spokes. Took a while to figure that out. Just another idea, the heat riser if still have could be it also
 

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That is great that you posted the recording.

I too think it is the exhaust.

But, it also sounds like small stones hitting the flywheel. Have you had the inspection cover off?

Good news is that when you find it, it's most likely going to be very simple and not internal to the engine.
 
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